Transformer



Oct. 25, 1932. c. H. THORDARSON TRANSFORMER Filed Feb. 11, 1931 INVENTOR.

- constant current type.

Patented Oct. 25, 1932 UNITED STATES PATENT OFFICE CHESTER H. THORDARSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO THORDARSON ELEC- TRIO MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OI ILLINOIS TRANSFORMER Application filed February 11, 1981. Serial 1T0. 515,014.

This invention relates to transformers and with particularity to transformers of the In certain of the arts, for example, the luminescent tube art, ordinary voltage transformers are not always practicable because of the varying voltages required during the starting and maintenance of the luminescent column. Furthermore in order that uniform brilliancy may be attained from such sources, it is desirable to employ a self regulating source of energy whereby the current supplied to the tube or lamp will remain substantially constant, notwithstanding vanations in the physical characteristics of the gas, or variations in the source of supply.

Accordingly one of the principal objects of this invention is to provide a constant current transformer which is eminently suitable for use with luminescent gas tubes such as neon lamps, or the like. It will be understood, however, that the invention is not limited to any particular use, but exhibits its advantages in any situation requiring a selfregulating current source.

A feature of the invention relates to a constant current transformer employing primary and secondary windings, together with a magnetic circuit therefor, all of which are symmetrically disposed with relation to each other.

Another feature of the invention relates to what may be termed a duplex transformer of the constant current type wherein the sections of the duplex transformer are provided with a common primary core.

Another feature of the invention resides in the provision of a pair of shell type transformers interconnected by a common primary core.

Another feature of the invention relates to a constant current transformer of the shell type employing a pair of primary windings and a secondary winding or windings disposed between the primary windings on a common core, together with magnetic shunt means interposed between each section of the primary winding and the secondary winding.

Another feature of the invention is to provide what may be termed a duplex constant current transformer which is eflicient in operation and readily assembled.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following detail descriptions and the appended claims.

Referring to the drawing Fig. l is a plan view of a duplex transformer according to the invention;

Fig. 2 is an end view of the transformer of Fig. 1.

Referring more particularly to the drawing, the transformer is shown as of the shell type having a central core portion 1, in the form of a pile-up of straight laminations. Surrounding the central core portion 1 are a series of windings designated by the numerals 2, 3, 4, 5, 6 and 7. The windings 2, 3 and 6, 7 are the primary windings and may be connected in series as represented in the drawing, or in series-parallel, or any other desired combination. The windings 4 and 5 are the secondary windings, and likewise may be connected in series or in parallel if desired. In the drawin the secondary windings 4 and 5 are of the ri bon type as shown by the numerals 8 and 9 which are the outer terminals of the windings. The opposite ends of the secondary windings 1 and 5 are connected together by a conductor 10, which thus provides a connection to the electrical midpoint of the secondary windin s. The main or central core 1 passes centraTly through each and every one of the windings. Associated with the windings 2, 3 and 4 are secondary mag netic cores disposed in butt contact on opposite sides of the core portion 1. These secondary core portions consist of substantially E-shaped lamination pile-ups comprising the legs 11, 12 and 13. The legs 11, 12 and 13 are connected to acommon leg 14. The secondary pile-ups are assembled so that the legs 11 and 13 are in butt contact with the primary or main core portion 1. The legs 12 are preferably fore-shortened with respect to the legs 11 and 13 to provide magnetic gaps 15 on opposite sides of the core portion 1. The function of the legs 12 and the gaps 15 is of the primary flux from the secondary Winding 4. The effectiveness of the shunt legs 12 increases in proportion to the magnetic flux theading the legs 13 and 14. In other words, as the secondary load increases the effectiveness of the shunts 12 correspondingly increases, thus tending to maintain the mag neto-motive force on the secondary winding substantially constant. It will be understood of course that the degree of regulation thus effected will be determined by the relative cross sections and reluctances of the shunt legs 12 and the secondary legs 13. While in the drawing the legs 13 are shown of substantially the same cross section as the legs 12, any othersuitable ratio of cross sections may be employed, and furthermore, while the secondary legs 13 are shown by smaller cross section than the legs 11 for certain purposes it may be desirable to make the legs 13 of the same cross section as the legs 11, or even of larger cross section, depending upon the regulating action desired in the transformer.

As will be obvious from the drawing there are provided in cooperation with the remaining windings 5, 6 and 7, secondary outer enclosing core portions similar to those associated with the windings 2, 3 and 4. There is thus provided in effect what may be termed a duplex transformer of the constant current type wherein all the windings are symmetrically disposed with relation to one another, and with relation to the central core 1.

Furthermore, because of the enclosing action of the outer core portion, the transformer as a whole is substantially unaffected by exterior magnetic electrical fields- Because of the symmetrical arrangement between the windings of the cores an accurately balanced transformer is provided. It will be understood, of course,that the several windclamped at their free ends,

ings shown in the drawing are suitably insulated from the core, forexample by theinsulating spacer elements16, 17, 18, 19. Be cause of the straight central core portion 1 it is possible to assemble the entire transformer expeditiously since all that is necessary is to pass the straight laminations through all of the windings, and then to position the outer E-shaped core portions in butt contact with the straight portion 1, after which any suitable clamping means may be provided for maintaining the entire core assembly rigidly in position. Since the shunt legs 12 are formed integrally with the legs 14, the said shunt legs do not vary their position as is the case with removable shunts. Furthermore, the shunt legs 12 may be riveted or otherwise thus preventing vibration with its consequent ill effects on the regulating action of the transformer.

Instead of employing a single continuous core 1 common to both sections of the duplex transformer, this core may be made in halves, thus in effect providing two separate constant current transformers, the windings of which may be connected in any suitable electrical arrangement. It is preferred to employ the common central core 1 as shown in the drawing, however, since it provides a simpler more symmetrical and more uniform regulating act-ion when the sections of the duplex transformer are operated together.

Various changes and modifications may be made in the structures disclosed without departing from the spirit and scope of the invention. For example, while the outer or secondary E-shaped core portions are provided on opposite sides of the portion 1, it will be understood that this arrangement is not absolutely necessary since only the one set of E-shaped laminations may be employed for each set of primary and secondary windings.

Furthermore, while the legs 11 are shown in butt contact with the ends of the core portion 1, it will be understood that any method of completing the magnetic circuit between the legs 11 and the portion 1 may be employed, for example by lapping or otherwise, as known in the transformer art.

What is claimed is:

1. A constant-current transformer comprising a central core portion, a primary winding and a secondary winding surrounding said central core, an outer enclosing core portion in the form of E-shaped laminations, the intermediate leg of each E-shaped lamination being fore-shortened with respect to the end legs, and providing a magnetic shunt between the primary and secondary windings. Y

2. A duplex-constant-current transformer comprising a pair'of primary windings, a pair of secondary windings, a single magnetic core extending through all said windings, and separate secondary cores, one for each set of primary and secondary windings.

3. A duplex-transformer according to.

claim ,2 in which the secondary cores enclose the windings. g

4. A duplex-transformer according to 1 claim 2 in which the secondary cores are substantially E-s'haped and are in butt contact with the said single core.

5. A core structure for a duplex transformer comprising a pair of E-shaped lamination pile-ups positioned adjacent each other with the legs thereof in non-opposing relation, and a single lamina-tion pile-up extending past each leg of the said E-shaped pile-ups.

6. A core structure 'for constant current transformers, comprising a pile-up of straight laminations, separate pile-ups of E-shaped laminations, the outer leg of each set of E-shaped pile-ups being in butt contact with the same face of the straight pile-ups.

7. A core structure according to claim 6 in which the intermediate legs of each of the E-shaped pile-ups is foreshortened to provide a gap to the straight pile-up.

8. A duplex transformer comprising separate transformer sections, each section including a primary and secondary winding, an enclosing magnetic core, and a common magnetic core for each of said sections.

9. A duplex transformer comprising separate transformer sections, each section including a primary and secondary winding and an outer enclosing magnetic core and a common central core for both said sections.

10. A transformer according to claim 9 in which the outer magnetic cores for each of the transformer sections is formed of E- shaped laminations.

11. A transformer according to claim 9 in which the outer enclosing cores are built up of substantially E-shaped laminations, the intermediate legs of the E-shaped lami nations being foreshor-tened to provide magnetic gaps to the common magnetic core.

12. A magnetic core for constant current transformers comprising a pile-up of straight laminations and separate sets of E-shaped lamination pile-ups disposed at opposite sides of said straight lamination pile-ups.

13. A magnetic core according to claim 12 in which the E-shaped laminations have their intermediate legs fore-shortened to provide magnetic gaps to the said straight laminations.

In testimony whereof I have hereunto set my hand on this 9th day of February, A. D.

CHESTER H. THORDARSON. 

